Department Of Physics
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Item Alloyed monolayers of Cu, Ag, Au and Pt in hexagonal phase: A comprehensive first principles study(Elsevier Ltd, 2018) Kapoor, Pooja; Kumar, Arun; Sharma, Munish; Kumar, Jagdish; Kumar, Ashok; Ahluwalia, P. K.We present density functional theory (DFT) based comprehensive study of two-dimensional (2D) alloyed monolayers of noble metals (AgCu, AgPt, AgAu, AuCu, AuPt and CuPt) in hexagonal phase within numerical atomic orbitals and plane wave basis sets methods. The monolayers considered exhibit positive phonon frequencies suggesting them to be dynamically stable. The Pt containing alloyed monolayers have superior structural stability (binding energy and tensile strength) and exhibit metallic and ferromagnetic character amongst all the alloyed monolayers. Interestingly, alloying of Au monolayer with Cu and Ag show semiconducting behavior whereas alloyed AgCu monolayer posseses Dirac-cone like features at high symmetry points. These distinct features in electronic structures of alloyed 2D monolayers have been captured in STM like set up. An anisotropic behavior has been observed in dielectric spectra for all the considered structures. Tunneling characteristics show NDR region for Pt containing alloyed monolayers. The considered alloyed monolayers may potentially be useful as a building blocks for the applications in nano- and opto-electronics. ? 2017 Elsevier B.V.Item Electronic, Mechanical, and Dielectric Properties of Two-Dimensional Atomic Layers of Noble Metals(Springer New York LLC, 2017) Kapoor, Pooja; Kumar, Jagdish; Kumar, Arun; Kumar, Ashok; Ahluwalia, P. K.We present density functional theory-based electronic, mechanical, and dielectric properties of monolayers and bilayers of noble metals (Au, Ag, Cu, and Pt) taken with graphene-like hexagonal structure. The Au, Ag, and Pt bilayers stabilize in AA-stacked configuration, while the Cu bilayer favors the AB stacking pattern. The quantum ballistic conductance of the noble-metal mono- and bilayers is remarkably increased compared with their bulk counterparts. Among the studied systems, the tensile strength is found to be highest for the Pt monolayer and bilayer. The noble metals in mono- and bilayer form show distinctly different electron energy loss spectra and reflectance spectra due to the quantum confinement effect on going from bulk to the monolayer limit. Such tunability of the electronic and dielectric properties of noble metals by reducing the degrees of freedom of electrons offers promise for their use in nanoelectronics and optoelectronics applications. ? 2016, The Minerals, Metals & Materials Society.